Friday Field Notes: Icy Sentinels: Stalwart Herons in Winter

Riding my bike in the summer along the Clark Fork River sometimes feels like an exhibition of nature. Munching beavers, darting kingfishers, and watchful Osprey are rarely out of sight or unheard. Trout break the surface of the river and grebes and their allies dip to catch a morsel under the cool water. But, as the warm clear mornings start to turn into cold ones and ice forms along the river's bank, only the hardiest animals show themselves.

A watchful eye in winter will turn up some of these unyielding creatures. One not too hard to spot is the Great Blue Heron. I was amazed to see that these large graceful birds were waiting at the edge of the ice, staring motionless into the water, as if mesmerized by the chunks of ice floating by. My thoughts then turned to a poem by renowned poet Mary Oliver--Herons in Winter in the Frozen Marsh.

http://writersalmanac.publicradio.org/index.php?date=2009/12/27

This poem captured much of the feeling I experience while watching these icy sentinels.

If you look carefully at some places on the river ice you can see their "pitchfork" footprints along the water's edge. You may be wondering how the herons can stand the cold with their long scaly legs in the frigid water or on the ice, and the answer is that they are equipped with a special routing of blood vessels in which the vessel carrying blood out to the leg lies directly against the vessel carrying blood back in. This is called "counter-current heat exchange," and is an adaptation used by many organisms across the globe. The blood going into the legs warms up the blood coming back into the body, keeping the heron's body temperature at a remarkable 103 to 106 degrees Fahrenheit (keep in mind that the average human body temperature is 98-99 degrees Fahrenheit). This allows them to stand at or in the water's edge and watch for fish and crustaceans for long periods of time.

As for me, I feel fortunate that I don't have to stand barefoot in the cold river to catch a bite to eat. I'm content just watching the pros at work.

So next time you find yourself along the river, make sure to scan for herons, motionless and cold, looking for lunch.

http://www.words4it.com/?tag=footprint

Friday Field Notes: On Bergmann's Rule, Ratios, and the Art of Staying Warm in Northern Climates

When MNHC's distinguished naturalists enter elementary school classrooms throughout western Montana this February for their monthly visit/natural history lesson, they will be discussing a fairly important ecological principle with 4th graders: Bergmann's rule. First articulated by German biologist Christian Bergmann (hence the name), the principle states that within a broadly distributed species or taxonomic group, an organism's body mass tends to increase with an increase in latitude (and the corresponding colder climate). While this principle has been most widely applied to mammals and birds, there are also examples of cold-blooded species that conform to the rule.

Why is such a principle observed in nature, you ask? Fundamentally, it is a function of larger animals exhibiting a decreased surface-area-to-volume ratio. Thus, larger-bodied animals lose less heat per unit of body mass, a characteristic that becomes vitally important in places like Montana where winters are long and cold. The following graphic helps better display this relationship:

Graphic displaying the mathematics underlying Bergmann's rule.

The important thing to note is the red text: While the larger cube has a considerably higher surface area, its volume has increased proportionately even more, thus lowering the surface-area-to-volume ratio.

Now, I know what you're thinking: Surface-area-to-volume ratios are a bit much for 4th graders. Most of us hadn't even heard of Bergmann's rule until our first college-level ecology course. But the science and mathematics underlying this stalwart of ecology can be easily explained and visualized. Consider this simple experiment, best suited for a brisk (32 degrees F or less) Montana winter day:

• Simultaneously fill up two cans of different sizes (i.e., a coffee can and a soup can) with near-boiling water. Place a thermometer in each can, and record the initial temperature.
• Place both cans outside. Record the temperature of each can every minute for approximately ten minutes.
• Afterwards, compare the change in temperature of the cans. The larger can should be significantly warmer than the smaller one, a result of its lower surface-area-to-volume ratio.

This simple experiment is a great way to test and conceptualize Bergmann's rule, and sheds light onto why being bigger is better when you live in northern latitudes. This fundamental relationship between surface area and volume explains why animals such as deer, elk, moose, and bears get larger as you move further north within their range. In some cases, the size difference can be quite dramatic. Male grizzly bears, for example, whose average weight is in the range of 500-1000 pounds in the Interior West, can reach up to 1,500 pounds in Alaska! In white-tailed deer, an incredibly far-ranging species, a similarly dramatic change is observed:

Bergmann's rule exhibited in white-tailed deer

So, if you're feeling guilty about those extra pounds you're still carrying around from holiday feasts or winter vacations, look on the bright side: You're going to stay much warmer this winter than you would without them!

Friday Field Notes: Winter's Other World

There's a whole other world out there that only exists in winter. The arrival of snow literally creates an entirely new habitat not found at any other time of the year. Naturalists know this place as the "subnivean environment."

While we might just see snow as powdery white stuff that accumulates as winter goes on, there is actually a lot happening underneath the surface. And indeed, the word subnivean, which means "under the snow" in Latin, suggests just that. As snow accumulates, it undergoes a variety of transformations: it compacts, melts, and refreezes. All of these changes form what we commonly think of as the snowpack. The snowpack can contain a variety of different layers, some hard, some soft, some deep, some shallow. These layers provide opportunities for small animals to create burrows, tunnels, and other structures that would be much more difficult to maintain in the soil, which is typically frozen throughout the winter.

Small mammals, like mice, voles, and shrews, likely could not survive outside of the subnivean environment. In addition to providing physical space for them to live in, the subnivean provides critical insulation. While the world above the surface is exposed to high winds and temperatures in the negatives, life underneath the snow remains a relatively cozy 32 degrees Fahrenheit! The other benefit of living in the snowpack is the protection it offers from predators.

Of course, these small mammals aren't totally safe. Have you ever seen this?

A fox dives into dinner head-first.

Foxes - as well as coyotes and some owls - are capable of hearing the movement of rodents underneath the snow. They wait patiently, honing in to the animals' exact location. And then, they pounce (or in the case of the owl, swoop). Extraordinary, no?

And then of course, there's this:

A marten emerges empty handed.

American Martens, like most other weasels, have never been afraid of digging in and getting a little dirty (or snowy?). Instead of listening for rodent movement and using stealth to catch their prey, they rely on power and speed to ramble through the snow and grab critters.

Next time you're out skiing or snowshoeing, imagine all the things that are going on beneath your feet! The snow isn't just snow; it's another world.

The Adel Mountains: Volcanic Pile

With over forty individually-named but unofficially delineated mountain ranges, Montana (from the Spanish word for mountain, montaña) is aptly named. The Rocky Mountain front cleaves down the northwestern portion of Montana, paralleling the Bitterroot, Flathead, Swan, Salish, and Mission Mountain ranges, while in the southwestern part of the state, the ranges are less of linear striations than variegated and somewhat disjointed bands of ridges jutting up like islands in the prairie.

http://images.summitpost.org/original/444328.jpg

Everyone in Montana, it would seem, recognizes the impressive Crazy Mountains; recreationalists love them for their plentiful alpine lakes, good fishing, and beautiful camping opportunities, and ranchers love them for the sweet grass they tower over. But nearby, a less known mountain range sits sentinel over a volcanic pile to the northwest.

2012 © Sara J. Call

If you have ever driven on I-15 from Great Falls to Helena (or vice versa), you may remember that you pass a sign identifying the Big Belt Mountains along the highway just past Cascade. The peaks rise impressively above, and if you continue on the highway , you will drop into a section of the Missouri River canyon to the northwest of the larger peaks. The interstate crosses the river, where log cabins have been built alongside the slow moving river. You may see a historic landmark sign that tells the story of the St. Peter’s Mission, made especially famous by Mary Fields, an emancipated slave who came to live with her former owner’s daughter, a nun that had helped establish the Mission. Mary’s strength and size came in handy in the repair of the mission’s dilapidated buildings, and she became the construction foreman; but when one of the workman who resented her struck her and reached for his pistol, she fired her six-shooter at him and was asked to leave the Mission. In 1895 when she was 60 years old, she was hired as a U.S. mail coach driver in Cascade and became known as the legendary Stagecoach Mary.

http://www.blackcowboys.com/maryfields.htm

 Continuing past St. Peter’s Mission, the interstate meanders through dark columnar igneous rock. While this range is adjacent to the Big Belt Mountain range, it is a separate range referred to as the Adel Mountains Volcanic Field.
Both the Little and the Big Belt mountains are not necessarily impressive in the same ways as other more popular mountain ranges in Montana; they are tall, and therefore a large portion of the peaks are above timberline, but they are also not heavily forested in general and are notably more rounded. There is not exceptionally good fishing or camping available, and only one part of the mountain range, the Gates of the Mountains, is designated wilderness. The area is forest service land, and popular for off-roading and horse-packing. The adjoining Adel Mountains (eroded to be no longer a recognizable volcanic cone) provide even less recreational opportunity, being a 40 mile long by 20 mile wide swath of almost vertical volcanic rock; but they possess a fascinating and uncommon geologic history.

Rod Benson © http://formontana.net/hardy.html

http://formontana.net/hardy.html

More than a billion years ago, two continental plates collided and formed what we call the Great Falls Tectonic Zone, a crustal weakness that lead to the volcanic creation of a series of mountains and buttes in the area and, most recently (around 75 million years ago), allowed magma to well up and create the Adel Mountains over top the surrounding sedimentary rock.

The Adel Mountain Volcanic Field is made of a rare type of intrusive igneous rock known as shonkinite, which is found only in Montana, British Columbia, Ontario, and the Indonesian island of Timor. It’s similar to basalt but more brittle, and principally contains augite and a type of feldspar.

From the interstate, you can see multiple dikes that radiate from the center of the formation zone; from within the canyon, the dikes are dark, vertical ridges (hint: look left at milepost 247 and right at milepost 250). These dikes often were the path magma followed to form laccoliths, which are intrusions of magma between layers of sedimentary rock that forced upper strata of rock upwards to form domes or buttes. Shaw Butte, Cascade Butte, and Square Butte were all formed in this way, and Square Butte has eroded enough to expose the actual laccolith volcanic formation within.

But you don’t need to be a historian or geologist to appreciate the Adel Mountains Volcanic Field. When I last drove through the area, the fresh layers of snow draped over the dark rock and sparkled like fish scales, and the wind picked up streams of shimmering snow and poured it over the edges of the cliffs like waterfalls. The snow crystals whirled around in the canyon and crashed against the raised road bed in the sunlight like a cold, white ocean wave, then snaked across the lanes of highway until dissipating like mist. It’s a magical area.



References:
http://www.bigskyfishing.com/Mountain-Fishing/belt_mountains.htm

http://www.cascademontana.com/mary.htm

https://docs.google.com/viewer?a=v&q=cache:8XO1-TvJs0QJ:mathscience.mt.gov/files/RoadSignPDF/Adel.pdf+&hl=en&gl=us&pid=bl&srcid=ADGEESh0lDMOJy2JJefzas4lHUc_H6eBTfZ-uxytmS7DKGQz3vl5QAAaB2u55h7R1xw2yx5uhUgLNMoSFR9hyD30XKALNUZLnKLEKzLTuigKlFTVh5d_tmO7fnp_0zY-4lukg1HmvlAc&sig=AHIEtbRRSLpC-pYQzaH3-To3SIbwOjZBIA

http://en.wikipedia.org/wiki/Adel_Mountains_Volcanic_Field

http://visitmt.com/categories/moreinfo.asp?SiteID=1&IDRRecordID=15520

Shonkinite

http://www.troutfishinglodgingmontana.com/gpage8.html



Spotlight On...Redtwig Dogwood

Redtwig Dogwood

Cornus sericea

Cornaceae (Dogwood Family)
Quick ID:

Redtwig dogwood is full of character throughout the year.  In its leafless winter state, the conspicuous red branches set off a blaze of color against the snow.

Early spring brings dense, flat-topped clusters of creamy white flowers, which give way to pea-sized white berries in summer.

Cooler temperatures bring out purple and red anthocyanins in the leaves--the mass fall display of a dogwood thicket can really take your breath away.  Look for this loosely spreading deciduous shrub, typically 6-12' high, growing in dense thickets in riparian areas and open forests.

The red twigs are tipped by a uniquely pointed terminal bud, and can be covered in lenticels on the old growth.  Leaves are opposite (arranged in pairs along the stem), simple (not lobed), with entire (not serrated) margins that tend to be wavy and occasionally rimmed in purple.

Notice the way the veins sweep up toward the tip of the leaf.  This is a great identifying feature that can be used to distinguish dogwood from the many other simple-leaved species out there (chokecherry, twinberry, huckleberry...I'm looking at you).

Range:
Very common throughout Canada and the northern US, south to Virginia on the east side and northern Mexico in the west.  Look for it growing in the rich, moist soil of riparian areas and in forest openings, in conjunction with alder (Alnus spp.), willow (Salix spp.), cottonwood and aspen (Populus spp.), Wood's rose (Rosa woodsii), currants (Ribes spp.), Rocky Mountain maple (Acer glabrum) and horsetails (Equisetum spp.).

What's in a Name?
Cornus is the Latin word for horn (like a unicorn).  The Romans called the dogwood "cornel", in reference to its wood, which is hard as the horn of a goat and useful for making a great many things.  This is also a convenient way to remember the distinct leaf buds of redtwig dogwood, which are narrow and pointed like horns.
The species name sericea means silky, in reference to the fine hairs covering the leaves.  The origin of the word "dogwood" itself is not totally settled.  It may be a corruption of "dagwood", from the use of its hard wood in making dags (or daggers).  Alternatively, there is some evidence that a concoction of English Cornus leaves was used to treat dog mange in 17th century herbology.
C. sericea is also commonly known as redosier dogwood.  This may be confusing, since "osier" comes from the medieval term for willow (Salix sp.)  In fact, the flexible young branches of C. sericea have long been used for basket weaving, much like the willows that grow in similar streamside thickets. 

Tidbits:
Like most of our native plant species, dogwood has been, and continues to be, valued for its many benefits to humans.  An extract made from the leaves, stems and inner bark can be used as an emetic for treating fevers and coughs (and a great many other ailments), and the inner bark scrapings have long been added to tobacco smoking mixtures.  The red stems not only produce colorful weaving patterns, but can be used to make red, brown and black dyes.

The white berries, although tart and bitter, are not poisonous, and have been eaten by many people throughout history.  The fruits are low in natural sugars, making them less attractive to wildlife and less likely to rot than other berries.  Thus, dogwood fruit persists long into the winter, making it available when other food is not.  These unlikely berries are a key food source of grizzly and black bears, and are also eaten by songbirds, waterfowl, cutthroat trout, mice and other animals.  Beavers use the hard wood to build dams and lodges.

Thickets of dogwood are especially good habitat for little birds like the dusky flycatcher, orange-crowned warbler, Lincoln sparrow and the house finch pictured here.  These thickets, often located along the river's edge, provide good places to rear young, with year-round security and food sources.  Because of its thick root system, redtwig dogwood is also important for stabilizing these streambanks, particularly in places where stream channels are scoured by seasonal flooding.

Wild Gardening

Being a water-loving species, Cornus sericea is tolerant of moist soils and varying water tables.  Once established, it also holds up well against drought.  Research has shown that water-stressed plants actually have a higher tolerance to freezing cold temperatures.  When dogwood senses the shortened days of oncoming winter, tissue changes occur that prevents the plant from taking up water and increases water lost through transpiration, so the tissue becomes dehydrated even when water is abundant.  This interesting adaptation, along with C. sericea's somewhat complex ability to avoid freezing injury by having water freeze outside of its cells, should make it an incredibly cold-hardy choice for northern gardeners.  BUT, remember the notorious cold snap of early October, 2009, when temperatures across Montana took a sudden dive into the single digits?  Our 11-year-old redtwig dogwood--10' tall and strong as an ox, we thought--was the only significant plant we lost at the Nature Adventure Teaching Garden here in Missoula.  Granted, all the plants at the NATG are dynamite no-fear natives that can take most anything the weather throws at them, so the garden's overwhelming hardiness came as no surprise.  The loss of Big Red was a sad one, though.
Luckily, dogwood is easy to propagate by seed, layering or stem cuttings, and easy to establish in a range of soils.  This is one shrub that will do fine in partial shade as well.  And while the tender stems are preferred browse for deer, elk and moose, they're less enticing that many of the delectable non-native shrubs commonly planted as ornamentals.  Aside from all the wildlife you'll be providing backyard habitat for, you'll also be enticing pollinators and butterflies with the fragrant white blossoms in spring (C. sericea is an important larval host for the Spring Azure (Celastrina ladon) butterfly.  Overall, this is one of the best all-purpose native shrubs to plant for ease of care and year-round enjoyment.

Thanks to Dave DeHetre, Bryant Olsen and Paul Alaback for some of the images used here.

Spotlight On... features Montana native plants that are currently on display in our natural areas.  Have a plant that you'd like to see featured?  Let us know!

Winter Adaptations of Three Montana Animals

Bears

                                                                                                                                                           

When we thinks of bears during winter, we commonly think of hibernation. But, in fact, bears do not hibernate at all. They go into what is called torpor, or short-term hibernation. Torpor helps bears save energy during winter when food is harder to find. When the animal is in torpor, its heartbeat and temperature go down, but not as much as in true hibernators. This aids animals such as bears in colder climates because it helps the animal conserve energy. This is not as deep a ‘sleep’ as hibernation and can last a very short time.

Unlike animals that go through hibernation, bears can wake up fairly easily. When they do, they will occasionally leave the den, but for the most part they do not eat or drink during winter.  During this time, a bear loses 15 to 30 percent of its body weight--without defecating or urinating.  Instead, the bear recycles its waste.  It does this by breaking down the urea, which at high levels is fatal.  The resulting nitrogen is used to build protein, allowing the bear to maintain muscle mass and organ tissue.

Bears and Their Cubs

The bear cub is born mid-winter, blind, hairless, helpless, and weighing less than a pound.  The tiny bear cub is just a fraction of one percent of the mother bear's weight.  "It's almost an external pregnancy--the cub is born and then migrates to the teats and nurses," said biologist John Hechtel. "The size of the cub in the spring when it comes out of den is closer to what you'd expect to see at birth." The reason for this is bear milk, which is very high in fat. The hibernating mother bear is living off her stored fat, and it's much more efficient for her to put that fat into her milk than to convert it to sugars and proteins that must be transported through her blood to the placenta, then through the placental barrier to the fetus. The mother also cleans the cub, and, by consuming the cub's waste, everything is recycled.

Grouse

Resting place of a ruffed grouse just after its departure

The ruffed grouse is famous for its winter roosting routine, commonly referred to as “snow roosting.” If the snow is soft and a foot or more deep, the grouse is likely to spend the night in an insulated, air-filled snow tunnel. To do this, the grouse will fly directly into the snow. Then, with its wings and feet, the grouse extends the tunnel, sometimes to as much as 10 feet. Recent research suggests that the temperature in the tunnel can be as warm as 32 degrees Fahrenheit and that it rarely falls below 20 degrees. The tunnel helps the grouse conserve energy, so it needs less food. Less time spent in the open also means less time being exposed to predators.

Ruffed grouse are poor at storing fat, so the winter months are tough. This means grouse must eat large amounts of food daily to survive. However, this poses a challenge. If the grouse feeds for too long, it risks being exposed to predators such as the red-tailed hawk and the great-horned owl. To minimize the risk, grouse eat fast. In as little as 20 minutes a grouse can swallow enough buds to make it through the day.

Ruffed grouse have other physical and behavioral characteristics that help in winter. In September, fleshy projections—called pectinations—begin growing on the sides of their toes and stay until spring. These comb-like nubs increase the surface area of the foot and work like snowshoes, allowing the bird to walk across snow with less effort. Pectinations also give the grouse a better grip on ice.

Grouse feathers also adapt in winter. In cold weather, special feathers extend down the beak and cover the nostrils. This allows the grouse to breathe in warm air. Ruffed grouse also have feathers partially covering and insulating their legs.

Moose

Bull moose eating willows

Moose are long-legged and thick-bodied, adaptations that enable them to move about through deep snow and wet lands and to carry sufficient fat stores. Their thick, hollow hair is fatter at the tip than at the base. The shape helps trap an efficient insulating layer of air next to their bodies. But staying warm is not all the moose has to worry about.

 

For moose, winter is full of suffering and triumph over that suffering. But the suffering is not as a result of the cold. Because of their winter adaptations, the cold hardly bothers them. The struggle that moose face is finding food. During winter, moose mostly eat twigs from deciduous trees and shrubs and the twigs and needles of balsam fir and cedar. Each bite of food is a mere gram–just 1/28th of an ounce. Furthermore, twigs and needles contain only one third the nutrition of leaves that moose eat during summer.

The food is not only low in nutrition, but worse off, difficult to gather. The snow is deep and moving from tree to tree is difficult and energy consuming. An 800- or 1000-pound moose survives the harsh winter, chest deep in snow moving from tree to tree, on about nine thousand twigs a day.

   

 When snow is deep and food sparse, moose restrict their intake of food because the costs of eating exceed the gains. Moose pass much of the winter resting and hungry. Ultimately, moose lose weight every single day for about five months of the year. Nevertheless, most moose live to see the spring that follows each winter.